A.20ppm—100ppm B.30ppm—100ppm C.40ppm—100ppm D.50ppm—100ppm
A.5.19 B.4.19 C.6.19 D.7.19
A.升華 B.遞進(jìn) C.轉(zhuǎn)化 D.轉(zhuǎn)變